Process of removing or recovering zinc from ores.



.and the percentage of zinc therein.

Patented July 11, 1905 PATENT OFFICE.

IVILLIAM STEWART, OF MOUNT FLORIDA, GLASGOW, SCOTLAND.

PROCESS OF REMOVING 0R RECOVERING ZINC FROM ORES.

SPECIFICATION formingpart of Letters Patent No. 794,198, dated July 11,1905.

Application filed June 28, 1904. Serial No. 214,451.

To (ti/7, whom, it may concern Be it known that 1, WILLIAM STEWART, acitizen of the United Kingdom of Great Britain and Ireland, residing at5 Cathkin Terrace, Mount Florida, Glasgow, Scotland, have invented acertain new and useful Improved Process of Removing or Recovering Zincfrom Ores, of which the following is a specification.

My invention relates to an improved process for removing or recoveringZinc from ores containing it, especially, but not exclusively, fromcomplex or refractory ores containing zinc together with gold andsilver, one of the objects being by removal of the zinc to facilitatethe recovery of the gold and silver contained in such ores by any knownprocess.

Under the present invention the ore is first pulverized and isthereafter intimately mixed with suitable proportions of bisulfate ofsoda or bisnlfate of potash and of common salt, the proportionsnecessarily varying according to the nature of the ores being treatedThe bisulfate of soda or bisulfate of potash may vary from about threeto about seventy percentum of the weight of the ore and the common saltfrom about two to about sixty percentum, according to circumstances. Themixture of pulverized ore and bisulfate of soda or bisnlfate of potashand common salt is put into a reverberatory or other suitable furnaceand is brought to a red heat and maintained thereat with a limitedsupply of air for about from fifteen minutes to three hours, the timevarying according to the nature of the ore being treated and thepercentage of zinc therein. Small charges are during the furnacing drawnfrom the furnace at short intervals, so that the condition of the zincin the mixture as to solubility may be ascertained and the heatmaintained or the charge withdrawn, according to the results indicated,

a too prolonged furnacing being in this way guarded against in order toprevent oxidation of the zinc or the soluble salts being split up andthe zinc again becoming insoluble. The Zinc is by this treatment broughtto the condition of salts soluble in water or slightly-acidulated water,and when testing of the small charges taken from the furnace indicatesthat the Zinc is wholly or almost entirely converted into such solublesalts then the charge is withdrawn from the furnace, allowed to cool,and thereafter leached or lixiviated in any ordinary manner. The zincsalts are thereafter precipitated and recovered by any known process. Inores containing gold and silver along with zinc, from which on accountof the presence of Zinc it is difficult or impossible to extract theprecious metals by ordinary known processes, the removal of the zinc inthe manner above described will enable the precious metal to be readilyextracted by such known processes.

Having now described the invention, what I claim, and desire to secureby Letters Patent, is-

A process for removing or recovering zinc from ores containing it, saidprocess consisting of pulverizing the ores, mixing therewith bisulfateof an alkali metal, and common salt, furnacing at a red heat andthereafter lixiviating or leaching and precipitating the zinc salts,substantially as set forth.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

WILLIAM STEWART.

Witnesses:

ROBERT BROWN, JAMES MoOLURE, Junr.

